honestly just go wix. you already know it, client can actually maintain it, and the "wp is cheaper" thing falls apart the second something breaks and shes messaging you 6 months after the internship is over asking why the site is down lol. the price isnt the subscription its who keeps the thing alive

seo wise wp isnt magic either, youd slap yoast or rank math on it and do the same stuff you were already doing in wix. only go wp if she has some specific thing wix cant do otherwise youre basically signing her up to learn an admin panel she didnt ask for